Multilayer Ceramic Capacitor Net Valence Control
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving a balance between high temperature accelerated lifetime characteristics and capacity stress aging characteristics, primarily due to the oxidation and reduction of the dielectric body during Cu baking, which affects the net valence of transition metals and subsequently impacts durability and capacitance stability.
Innovation Solution
The use of a dielectric ceramic composition with specific ratios of barium titanate, Mg and Ca oxides, SiO2, Mn and Cr oxides, and rare earth elements, where the net valence of Mn and/or Cr is controlled between 2.2 and 2.4, along with precise control of oxygen partial pressure and hydrogen concentration during firing and annealing processes, to optimize the oxidation and reduction states, thereby enhancing the capacitor's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu baking is performed at high temperature close to annealing temperature, then terminal electrode formation is achieved, but dielectric body undergoes reduction and oxidation affecting lifetime and aging characteristics
Solution Approach 1:
The patent applies parameter changes by precisely controlling the net valence of transition metals (Mn and Cr) within the range of 2.2 to 2.4, and by controlling oxygen partial pressure and hydrogen concentration during Cu baking. These parameter adjustments optimize the oxidation and reduction states of the dielectric body, resolving the contradiction between achieving terminal electrode formation and maintaining dielectric body stability.
2Reliability
If net valence of Mn and Cr is controlled within specific range, then oxidation and reduction states are optimized, but manufacturing complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for net valence of Mn and Cr (2.2 to 2.4), oxygen partial pressure, and hydrogen concentration during Cu baking. By defining these precise parameter ranges, the patent optimizes capacity stress aging characteristics while providing clear manufacturing guidelines that balance complexity with performance improvement.
3Productivity
If sintering is performed at low temperature for short time, then productivity is improved, but oxidation and reduction control becomes difficult
Solution Approach 1:
The patent enables low-temperature, short-duration sintering by controlling the net valence of Mn and Cr within 2.2 to 2.4, along with specific oxygen partial pressure and hydrogen concentration. These parameter changes allow rapid sintering while maintaining precise oxidation and reduction control, thus improving productivity without sacrificing manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in improved high temperature accelerated lifetime and capacity stress aging characteristics, ensuring superior durability and stability of the multilayer ceramic capacitors by maintaining the optimal net valence of transition metals within the dielectric body.
Implementation Method 1
a dielectric body is reduced and oxidized due to an atmosphere at Cu baking
Implementation Method 2
a dielectric body is reduced and oxidized due to an atmosphere at Cu baking
Data Source
AI summary
Electronic device 1 comprises an element body 10, comprising a dielectric layer 2 constituted by a dielectric ceramic composition, and a terminal electrode 4, formed outside of the element body 10. The dielectric ceramic composition comprised a main component including barium titanate; a first subcomponent including at least one oxide of Mg and Ca; a second subcomponent including SiO2; a third subcomponent including at least one oxide of Mn and Cr; and a fourth subcomponent including an oxide of rare earth elements, wherein the net valence of Mn and/or Cr in the third subcomponent is 2.2 to 2.4. According to the electronic device 1, both high temperature accelerated lifetime characteristics and capacity stress aging characteristics can be improved in a balanced manner.